43 tests for a module that exists solely to slow itself down.
That is what warmup.py is. A rate governor that tracks whether it should let you write at all, and the bulk of the logic is about deciding to stop, roll back, or halt entirely. The evaluate() state machine advances only when four gates pass simultaneously: dwell time, no sustained 344s, health, and impressions. If a trailing seven day window shows a code 226, it rolls back a phase. Hit that rollback twice at the same phase, and the whole thing halts and fires an alert.
The interesting design decision is over_ceiling(). It returns False when warm up is disabled entirely, True when halted, and otherwise just checks whether writes today exceed the ceiling for the current phase. Three semantically distinct states collapsed into a boolean, which sounds like a shortcut until you realize the caller only ever needs to know one thing: should I write right now? The boolean is the right abstraction because the reasons not to write are an implementation detail.
The 43 test suite covering every public function and the full state machine is the part worth talking about. Most people writing automation write tests for the happy path and call it done. The state machine here has rollback logic, halt logic, a ceiling that varies by phase, and a reset hook. Every one of those branches needs a test because the failure modes are asymmetric: a false negative means you do not post, a false positive means you get rate limited and potentially flagged. The cost of writing the wrong thing is much higher than the cost of writing nothing.
Shipping this without the 43 tests would have been faster. It also would have been a guarantee that the rollback logic breaks in some edge case six weeks from now when nobody is watching.